Computers connected by networks have become a common means of communication. Modern computer networks may have many millions of nodes and, as a result, much of the virtue and, in particular, vice of any larger community. At times, there is a need for secure communication between computers. This is true even of smaller computer networks. Such secure communication may include private communication as well as authenticated communication. Of the methods for achieving secure communication, methods based on cryptography are among the most reliable and popular.
Cryptographic protocols securing communication typically have one or more parameters, some of which may not be explicit. For example, a specification of a cryptographic protocol may specify some parameters as required and others as optional. In addition, the cryptographic protocol may have parameters that are not explicitly set forth in the specification. Although protocol designers may make efforts to minimize such parameters.
An adversary desiring to compromise a particular cryptographic protocol may attempt to characterize one or more of the parameters of the cryptographic protocol. At least one parameter of the cryptographic protocol is typically designed to be resistant to such characterization. A cryptographic protocol with multiple characterization-resistant parameters may be more secure.
A problem is that, over time, protocol parameters may become less resistant to characterization, for example, because of technical advances. Another problem is that protocol parameters may not be as resistant to characterization as commonly believed. The cryptographic protocol may even have parameters, perhaps not known to the protocol designers, that are relatively easy to characterize. Characterization of one parameter, even if it does not lead to direct security compromise, may lead to characterization of some other, perhaps more significant parameter. Parameter regularities, in particular, may be a problem.